Obeblin smith



(No Model.)

0. SMITH.

SPRING KEY. No. 362,548.

Patented May 10. 1887.

Fig.2. Fig.3.

Fig.5.

Fig.6. 7

.Ct'R. Fl 37. F|g8 WITNESSES:

. v V I V INVENTOR fimm l i 7 W UNITED STATES PATENT OFFICE.

O-BERLIN SMITH, OF BRIDGETON, NEW JERSEY.

SPRING-KEY.

SPECIFICATION forming part of Letters Patent No. 362,548, dated May 10,1887.

Application filed August 11, 1886. Serial No. 210,659. (No model.)

To all whom, itmay concern.-

Be it known that I, OBERLIN SMITH, a citizen of the United States,residing at Bridgestruction and design shown in the accompanyingdrawings, in which I will first illustrate, in Figures lto 5, how such aresult has not heretofore been attained by the keys and cotters whichare now in the market.

In Fig. l is shown a side view of the oldfashioned spring-key, Fig. 2being a crosssection of the same at a, Fig. 1, and Fig. 3 acrosssect-ion at b, Fig. 1, both-views being looked at from the headend, or from the direction of a toward b. V Fig. 2 shows the key open,and Fig. 3 shows it closed together at the point, so that it may beinserted in the hole, which is represented by the dotted circle 0. Itwill be noticedthat this hole is much larger than the body or thecylindrical part of the key between a and b, and therefore the key mustbe 'a very loose fit, thus making it unsuitable for many purposes whereshaking about is to be avoided ,and where a maximum diameter, andconsequent strength of key, must be combined with a minimum diameter ofhole in the bolt, shaft, or other rod through which the key is inserted,in order that said rod may not be too much weakened thereby. Fig. 4shows the side view of what is commercially termed a spring-cotter, madewith no enlargement at its point to prevent its sliding out of its hole.This is a useful device when it can remain permanently in the hole,

because it is not sure to stay in the hole by the action of frictionalone, even though its elasticity causes it to spring apart withconsiderable force.

In Fig. 6 is shown a side view of my new spring-key, which is thesubject of this invention, as it appears when inserted entirelyinto itshole, with its points opened by its own elasticity as far as the sidesof the hole will allow;

In Figs. 7 and 8 are shown cross-sections at a and 1), representedlooking in the same direction as above mentioned for Figs. 2 and 3.

Fig. 9 shows a side view of the same key inserted part way into itshole, with its points sprung together, so as to reduce it to its properdiameter.

Figs. 10 and 11 show the respective crosssections at a and b, as before,the section-lined circle marked D in Figs. 6 and 9 being of course across-section (through the axis of the key-hole) of the rodthrough'which the key is inserted.

In Figs. 12, 13, and 14 are shown similar upon the same principle; butthe cylindrical oneis more particularly the subject of this invention.

It will be seen from the foregoing that the main idea involved in myinvention consists in making a spring-key whose body is cylindrical andfits its hole, while its point is furnishedwith approximatelyright-angled shoulders of a larger diameter than the hole, to preventits being withdrawn unless it is forcibly sprung together. It consists,furthermore, in making the wedge-shaped slit between the two arms of thekey of such proportions that when it is entirely closed by the pointsbeing sprung together the total diameter of such points will be equal toor less than the size of the body at a, so that it can be put throughthe hole.

As shown in Fig. 9, it will be noticed that the desired result is hereobtained without weakening the key, because the full diameter isretained at a, and the less amount of crosssection at 12 only makes eacharm of the key a tapering lever or projecting beam, which, it is wellknown, is within certain limits just as strong as if the said lever orbeam were parallel or of equal cross-section throughout.

Any such lever may be of less than half the thickness at its outer endthat it is at its inner end without being weakened by such taper, and itis also of the proper shape to bend uniformly without bringing thestresses mostly at one place, as is the case when the lever is parallel.

There are Various methods by which this form of key can be easilymanufactured, either by machine-forging or by making it first in theform of Fig. 4, and then milling or turning the body to a cylindricalform while the points are held the proper distance apart by a speciallyadapted chuck, preferably furnished with a projecting wedge to enter andfit the slot between the arms. The latter is the method which I haveused with perfect success in my own practice.

